Accelerator pump controlled engine spark timing

ABSTRACT

The vacuum line between the carburetor spark port and the engine distributor breaker plate servo actuator includes an air bleed valve that is normally closed to permit normal advance of the engine timing as a function of spark port vacuum changes, but is opened by a servo actuated directly by the carburetor accelerator pump linkage during vehicle accelerations to bleed air to the distributor servo to condition the timing for retarded operation.

United States Patent Vartanian [54] ACCELERATOR PUMP CONTROLLED ENGINESPARK TIMING [72] Inventor: Richard D. Vartanian, Dearborn,

Mich.

[73] Assignee: Ford Motor Company, Deal-born,

Mich.

221 Filed: Dec.2, 1970 21 Appl. No.: 94,361

[52] US. Cl. ..l23/l17 A [51] Int. Cl ..F02p 5/10 [58] Field of Search..123/117 [56] References Cited UNITED STATES PATENTS 2,361,271 10/1944Colvin ..l23/ l 17 A 2,650,581 9/1953 Short ..123/117 A [451 Oct. 24,1972 3,289,659 12/1966 Koole ..123/1 17 A 3,431,897 3/1969 Eltinge..l23/l17 A 3,476,094 11/1969 Rucins et a1. 123/1 17 A PrimaryExaminerLaurence M. Goodridge Assistant ExaminerCort Flint Attorney-JohnR. Faulkner and Robert E. McCollum 5 7] ABSTRACT The vacuum line betweenthe carburetor spark port and the engine distributor breaker plate servoactuator includes an air bleed valve that is normally closed to permitnormal advance of the engine timing as a func tion of spark port vacuumchanges, but is opened by a servo actuated directly by the carburetoraccelerator pump linkage during vehicle accelerations to bleed air tothe distributor servo to condition the timing for retarded operation.

9 Claims, 1 Drawing Figure PATENTED T 24 I973 WWW T 0 N 0 E/ V f N a l1/ fl W W K A 2/ M Z H U wamw,

AT TORN EYS ACCELERATOR PUMP CONTROLLED ENGINE SPARK TIMING Thisinvention relates, in general, to a device that aids in the reduction ofexhaust emission pollutants from an internal combustion engine. Morespecifically, it relates to a mechanical spark timing control devicethat eliminates carburetor spark port vacuum to the distributor duringvehicle accelerations in response to operation of the carburetoraccelerator pump.

Most present day motor vehicles have some sort of a vacuum servoautomatically controlling the advance or retard setting of the enginedistributor breakerplate as a function of carburetor spark port vacuumto provide good engine performance as well as fuel economy during thedifferent operating conditions of the engine. These vacuum servos, intheir simplest forms, generally consist of a housing divided intoatmospheric pressure and vacuum chambers by a flexible diaphragmconnected to the distributor breaker plate. The diaphragm and breakerplate are normally spring biased to the lowest advance or retard sparktiming setting, and carburetor spark port vacuum normally urges thediaphragm in a spark timing advance direction upon opening of thecarburetor throttle valve in an engine speed increasing direction.

With the above construction, vehicle accelerations from an idle speedcondition cause vacuum at the carburetor spark port to act on the oneside of the servo diaphragm to immediately move the distributor breakerplate to an advanced setting. This provides a longer burning time forthe fuel mixture before the optimum top or near top dead center positionof the piston is attained, generally providing the most desirableoperation. However, this longer time permits a build-up to highercombustion temperatures and pressures, which is undesirable insofar asthe production of oxides of nitrogen and other undesirable elements areconcerned.

It will be seen, therefore, that the conventional spark timing controlsystems may provide good performance and fuel economy, but do notnecessarily minimize the output of undesirable exhaust gas elements.

Therefore, it is a primary object of the invention to provide an enginespark timing device that has the advantages of the conventional sparktiming control system while minimizing the disadvantages; by providing adevice that retards the spark timing during vehicle accelerations, todecrease NO x output, while extending burning of the mixture into theexhaust system to reduce the amount of exhaust gas emission of otherundesirable elements.

It is another object of the invention to provide an engine spark timingcontrol system including a device that meets the requirements set outimmediately above, by including an accelerator pump linkage actuatedatmospheric pressure air bleed in the vacuum line to the distributorservo to bleed spark port vacuum during vehicle accelerations.

Other objects, features and advantages of the invention will become moreapparent upon reference to the succeeding detailed description thereof,and to the drawing illustrating a preferred embodiment thereof; whereinthe FIGURE illustrates schematically a crosssectional view of an enginespark timing control apparatus embodying the invention.

The FIGURE shows, schematically, only those portions of an internalcombustion engine that are normally associated with the enginedistributor spark timing setting control; such as, for example, acarburetor 10, a distributor breaker plate 12, a vacuum servo 14 tocontrol the movement of breaker plate 12', and a line 16 connectedbetween the carburetor and vacuum servo to automatically change theengine spark timing setting as a function of changes in engine vacuumspark port setting.

More specifically, carburetor 10 is shown as being of the downdraft typehaving the usual air-fuel induction passage 18 with an atmospheric airinlet 20 at one end and connected to the engine intake manifold 22 atthe opposite end. Passage 18 contains the usual fixed area venturi 24and a throttle valve 26. The latter is rotatably mounted on a part ofthe carburetor body across passage 18 in a manner to control the flow ofairfuel mixture into the intake manifold. Fuel-would be inducted in theusual manner from a nozzle, not shown, projecting into or adjacentventuri 24, in a known manner.

Throttle valve 26 is shown in its engine idle speed position essentiallyclosing induction passage 18, and is rotatable to a nearly verticalposition essentially unblocking passage 18. A spark port 28 is providedat a joint just above the idle position of throttle valve 26, to betraversed by the throttle valve during its opening or part throttlemovements. This will change the vacuum level in spark port 28 as afunction of the rotative position of the throttle valve, the spark portreflecting essentially atmospheric pressure in the air inlet 20 uponclosure of the throttle valve.

As stated previously, the distributor, not shown, in-

Y cludes a breaker plate 12 that is pivotally mounted at 30 on astationary portion of the distributor, and movable with respect to cam32. The latter has six peaks 34 corresponding to the number of enginecylinders. Each peak cooperates with the follower 36 of a breaker pointset 38 to make and break the spark connection in a known manner for eachone-sixth, in this case, rotation of cam 32. Pivotal movement of breakerplate 12 in a counterclockwise spark retard setting direction, or in aclockwise spark advance setting, is provided by an actuator 40 slidablyextending from vacuum servo 14.

Servo 14 may be of a conventional construction. It has a hollow housing42 whose interior is divided into an atmospheric pressure chamber 44 anda vacuum chamber 46 by an annular flexible diaphragm 48. The diaphragmis fixedly secured to actuator 40, and is biased in a rightward retarddirection by a compression spring 50. Chamber 44 has an atmospheric orambient pressure vent, not shown, while the chamber 46 is connected toline 16.

During engine-off and other operating conditions to be described,atmospheric pressure exists on both sides of the diaphragm 48,permitting spring 50 to force the actuator 40 to the lowest advance or aretard setting position. Application of vacuum to chamber 46 movesdiaphragm 48 and actuator 40 toward the left to an engine spark timingadvance position, by degree, as a function of the change in vacuumlevel.

Turning now to the invention, an air bleed device 52 is located in line16 between servo 14 and spark port 28. The device 52 includes a valvebody 54 defining a three passage fluid chamber 56. Passage 58 is a ventand connects to atmospheric pressure. Passage 60 is connected to servoline 16, and passage 62 is connected to spark port 28.

A valve member 64 is sealingly mounted to slide through chamber 56, asshown. it includes a main cylindrical body portion 66, a reduceddiameter end actuator portion 68, and a conical intermediate portion 70.The conical portion 70 is adapted to seat at times against a matinglyformed portion 72 of body 54 to cut 011' vacuum flow from spark port 28to servo chamber 46. Simultaneously, the downward movement of valve 64engages the end 68 with a flexible reed-like valve 74 to bend open thesame and connect line 60' to atmospheric pressure. The valve 74 isfixedly riveted or otherwise mounted at one end to body 54, as shown.

The upper end of valve 64 is fixed to an annular flexible diaphragm 76that forms one wall of an air chamber 78. The opposite wall of thechamber is defined by a second annular flexible diaphragm 80 that issealingly mounted across the center of a hollow housing 82. An actuatinglever 84 is fixedly secured to diaphragm 80, and slidingly projectsthrough a boss 83 in the housing, as shown. Air leaking along the shaftmaintains chamber 86 at atmospheric pressure.

The actuator 84 forms an integral part of the conventional carburetoraccelerator pump linkage, not shown. As a result, it moves verticallyconcurrently with movement of the throttle linkage to open throttlevalve 26 during vehicle accelerations, in a known manner. Lever 84 willbe returned to the position shown by the conventional throttle returnspring, not shown, upon release of the vehicle accelerator pedal by theoperator.

Completing the construction, chamber 78 includes an air bleed consistingof an orificed passage 88 that slowly bleeds the air pressure in chamber78 at times, and at other times restores chamber 78 to an atmosphericpressure level.

In operation, at engine start up, both chambers 78 and 86 are at ambientor atmospheric pressure as are both sides of the servo 14. Accordingly,a spring 90, seated between housing 54 and diaphragm 76, has biasedvalve 64 upwardly to permit bleed valve74 to close, and the distributorbreaker plate 12 has been rotated by spring 50 to its maximum retardspark timing position.

The condition described above also is applicable during engine idlespeed operation, in that the pressure in spark port 28 then isessentially atmospheric, or that in the air inlet portion 20.

Assume now that thevehicle accelerates lightly, throttle valve 26rotating counterclockwise. Immediately spark port 28 is subject tovacuum in the intake manifold 22. Though low, vacuum acting throughchamber 56 normally would permit the atmospheric pressure in chamber 44to compress spring 50 and move the breaker plate 12 towards a sparktiming advance position. However, movement of the throttle valve linkagesimultaneously moves the accelerator pump lever 84. This does twothings. First, movement of diaphragm 80 downwardly pressurizes chamber78. Secondly, diaphragm 76 is moved downwardly against spring 90 to seatvalve 64 to block line 62 while simultaneously opening bleed valve 74.This maintains passage 60 at atmospheric pressure and, therefore, servochamber 46. Accordingly, breaker plate 12 is maintained in the maximumengine spark retard position.

As the acceleration of the vehicle proceeds, the leakage of air pressurefrom chamber 78 through bleed 88 permits the spring 90 to move diaphragm76 upwardly. When the pressure in chamber 78 has reduced, valve 64 willreturn to its original position shown. This effects a slow closing ofair bleed valve 74 with a consequential slow buildup of vacuum in line60 from the spark port 28. When the pressure in chamber 78 is reduced,the spark timing plate 12 will assume the advance position dictated bythe vacuum in line 62.

If, during the accelerating operation, the throttle valve is suddenlymoved to a closed position, indicating a decelerating operation, theaccelerating pump lever 84 is returned to the full line position byspring means not shown. This decays the pressure in chamber 88, andpermits spring 90 to move diaphragm 76 upwardly. This upward movementunseats valve 64 and closes bleed valve 74. However, since essentiallyatmospheric pressure is prevalent at spark port 28, the breaker plate 12will be maintained at a maximum retard setting.

From the above, it will be seen that the invention conditions the enginespark timing for a maximum retard setting during engine acceleratingoperations and maintains that retard setting during vehicledecelerations. it will also be seen that the device permits normaladvance of the spark timing.

I claim:

1. A motor vehicle engine spark timing control system comprising, anengine carburetor having an induction passage containing a spark portlocated above the idle speed position of a throttle valve controllingflow through the passage and subject to the depression in the carburetoras a function of the movement of the throttle valve from its idle speedposition, an engine distributor having a breaker plate pivotally movablein opposite directions to advance and retard the spark timing, sparkport connected vacuum controlled servo means connected to said breakerplate for moving the same normally solely as a function of spark portvacuum changes, and control means between said spark port and servomeans to control the application of vacuum from said spark port to saidservo means, said control means including conduit means connecting thevacuum at said spark port to said servo means for effecting variablemovement of said breaker plate from a maximum retard setting at closedthrottle valve idle speed position to a maximum advance setting at highspark port off-idle vacuum levels, and an air bleed means openable inresponse to vehicle acceleration demand independently of spark portvacuum level to momentarily bleed air to said servo means to positionsaid breaker plate at a maximum retard setting, said air bleed meansincluding a normally closed atmospheric pressure vent in said conduitmeans, and a valve movable through said conduit means to block the fluidsignal from said spark port while simultaneously opening said vent toconnect said servo means to atmospheric pressure.

2. A control system as in claim 1, including a second movable valvenormally closing said vent and movable by said first mentioned valve toopen said vent.

3. A control system as in claim 2, said second valve comprising a flatflexible reed-like valve bendable by said first mentioned valve.

4. A control system as in claim 1, including manually operable meansoperably connected to said valve for moving the same in a direction toopen said vent, and spring means biasing said valve in the oppositedirection.

5. A control system as in claim 4, said carburetor including an operatormovable accelerator pump linkage, said manually operable meanscomprising link means adapted to be operably connected to the pumplinkage so as to be movable concurrently therewith upon movement of saidlinkage by the vehicle operator.

6. A control system as in claim 4, including second servo means betweensaid manually operable means and said valve for operably moving saidvalve to open said vent.

7. A control system as in claim 6, said second servo means includingahollow housing, a pair of flexible diaphragms in said housing defininga fluid pressure chamber therebetween, a second air vent connected tosaid chamber, a flow restrictor in said second air vent, and meansconnecting one of said diaphragms to said valve and the other of saidpair of diaphragms to said manually operable means whereby movement ofsaid latter means effects a movement of said valve to open said firstmentioned vent, said flow restrictor defining a time delay bleed ofpressure from said chamber for the return movement of said firstdiaphragm and valve to effect closing of said first mentioned vent.

8. A control system as in claim 7, said air bleed means comprising aflat reed-like flexible valve normally closing said first mentioned ventand bendable by said first mentioned valve upon engagement thereby to aposition opening said latter vent.

9. A spark timing control system comprising, an engine carburetor havingan induction passage containing a spark port located above the idlespeed position of a throttle valve controlling flow through the passageand subject to the depression in the carburetor as a function of themovement of the throttle valve from its idle speed position, an enginedistributor having a breaker plate pivotally movable in oppositedirections to advance and retard the spark timing, vacuum controlledservo means connected to said breaker plate for moving the same, andflow rate control means between said spark port and servo means tocontrol the rate of change of application of vacuum from said spark portto said servo means, said control means including conduit meansconnecting the vacuum at said spark port to said servo means fornormally effecting variable movement of said breaker plate from amaximum retard setting at closed throttle valve idle speed position to amaximum advance setting at high spark port off-idle vacuum levels solelyas a function of spark port vacuum changes, and an air bleed meansopenable independently of the spark port vacuum by and in response tomovement of the accelerator pump linkage of said carburetor to bleed airto said servo means during accelerative modes of operation of saidvehicle while simultaneously shutting off a portion of the conduit meanscontaining the spark port vacuum.

1. A motor vehicle engine spark timing control system comprising, anengine carburetor having an induction passage containing a spark portlocated above the idle speed position of a throttle valve controllingflow through the passage and subject to the depression in the carburetoras a function of the movement of the throttle valve from its idle speedposition, an engine distributor having a breaker plate pivotally movablein opposite directions to advance and retard the spark timing, sparkport connected vacuum controlled servo means connected to said breakerplate for moving the same normally solely as a function of spark portvacuum changes, and control means between said spark port and servomeans to control the application of vacuum from said spark port to saidservo means, said control means including conduit means connecting thevacuum at said spark port to said servo means for effecting variablemovement of said breaker plate from a maximum retard setting at closedthrottle valve idle speed position to a maximum advance setting at highspark port off-idle vacuum levels, and an air bleed means openable inresponse to vehicle acceleration demand independently of spark portvacuum level to momentarily bleed air to said servo means to positionsaid breaker plate at a maximum retard setting, said air bleed meansincluding a normally closed atmospheric pressure vent in said conduitmeans, and a valve movable through said conduit means to block the fluidsignal from said spark port while simultaneously opening said vent toconnect said servo means to atmospheric pressure.
 2. A control system asin claim 1, including a second movable valve normally closing said ventand movable by said first mentioned valve to open said vent.
 3. Acontrol system as in claim 2, said second valve comprising a flatflexible reed-like valve bendable by said first mentioned valve.
 4. Acontrol system as in claim 1, including manually operable means operablyconnected to said valve for moving the same in a direction to open saidvent, and spring means biasing said valve in the opposite direction. 5.A control system as in claim 4, said carburetor including an operatormovable accelerator pump linkage, said manually operable meanscomprising link means adapted to be operably connected to the pumplinkage so as to be movable concurrently therewith upon movement of saidlinkage by the vehicle operator.
 6. A control system as in claim 4,including second servo means between said manually operable means andsaid valve for operably moving said valve to open said vent.
 7. Acontrol system as in claim 6, said second servo means including a hollowhousing, a pair of flexible diaphragms in said housing defining a fluidpressure chamber therebetween, a second air vent connected to saidchamber, a flow restrictor in said second air vent, and means connectingone of said diaphragms to said valve and the other of said pair ofdiaphragms to said manually operable means whereby movement of saidlatter means effects a movement of said valve to open said firstmentioned vent, said flow restrictor defining a time delay bleed ofpressure from said chamber for the return movement of said firstdiaphragm and valve to effect closing of said first mentioned vent.
 8. Acontrol system as in claim 7, said air bleed means comprising a flatreed-like flexible valve normally closing said first mentioned vent andbendable by said first mentioned valve upon engagement thereby to aposition opening said latter vent.
 9. A spark timing control systemcomprising, an engine carburetor having an induction passage containinga spark port located above the idle speed position of a throttle valvecontrolling flow through the passage and subject to the depression inthe carburetor as a function of the movement of the throttle valve fromits idle speed position, an engine distributor having a breaker platepivotally movable in opposite directions to advance and retard the sparktiming, vacuum controlled servo means connected to said breaker platefor moving the same, and flow rate control means between said spark portand servo means to control the rate of change of application of vacuumfrom said spark port to said servo means, said control means includingconduit means connecting the vacuum at said spark port to said servomeans for normally effecting variable movement of said breaker platefrom a maximum retard setting at closed throttle valve idle speedposition to a maximum advance setting at high spark port off-idle vacuumlevels solely as a function of spark port vacuum changes, and an airbleed means openable independently of the spark port vacuum by and inresponse to movement of the accelerator pump linkage of said carburetorto bleed air to said servo means during accelerative modes of operationof said vehicle while simultaneously shutting off a portion of theconduit means containing the spark port vacuum.